My brother failed inspection on his Sunbird for emissions. Here is the diagnostic:
GAS: NOx
STANDARD: 1088
READING: 1464
RESULT: FAIL
Is this something a new oxygen sensor will remedy? I really don't want to do any emissions related work besides that, ha. Thanks for any advice!
I forgot to mention it is a 1994 Sunbird, I think a 3.1 L V6.
Assuming that all of the other gasses passed, I would mostly concentrate on the EGR valve. I believe that those engines had an external line going from the exhaust to the valve that looked somewhat like corrugated tubing. If this has a leak in it, it can cause that failure. Any blockage in the EGR passages can certainly cause the problem too, so you may have to remove the valve to inspect the passages also. Make sure you have a new gasket handy first though - otherwise you could create a nasty vacuum leak and make things worse.
NOX is generated by high combustion temperatures. The EGR valve allows burnt exhaust gasses to dilute the mixture, which lowers the peak flame temperature. Over-advanced ignition timing can also cause this problem - but I believe that there
should be a knock sensor on that motor to limit that. An engine that's running hot could probably contribute somewhat, but not likely enough to cause your problem.
Hopefully this helps a bit...
John
Thank you John. That is useful information.
Fortunately I dodged a more expensive repair for the time being. I replaced the oxygen sensor and passed! Mwahahaha! Unfortunately since the car was not inspected for so long I have to go back in January, so I fear the EGR valve may need some tampering yet. There is a chance you haven't seen the last of me.
